This invention relates to the nuclear art and it has particular relationship to nuclear reactors for supplying electrical power. In the interest of safety and reliability, the cost of constructing and installing a nuclear power plant has increased to a high level. In view of the high investment demanded, it is desirable that the economics of the power reactor be such as to moderate the rate structure to the extent practicable. It is accordingly an object of this invention to provide a nuclear reactor for electrical power purpose in whose use and operation material reduction in rates as compared to current reactors shall be obtainable.